The federal government is at the precipice of another shutdown, this time a partial one, if Congress can’t reach an agreement soon on seven outstanding appropriations bills. The deadline to pass those bills was this Friday, Dec. 7, at midnight, but the funeral for former president George H.W. Bush complicated that schedule, so the lawmakers have agreed to push the deadline back two weeks, until Dec. 21.

Let’s take a quick look at all that is at stake this month.

Why would it be a partial shutdown?

Lawmakers were quite proud of themselves this year when they were able to pass brand new spending bills for important areas such as defense, education, veterans affairs and energy, so all of those related agencies and programs are securely funded for fiscal 2019. But Congress couldn’t finish seven other appropriations bills before the midterms, so they packaged them together in a short-term continuing resolution that they set to expire Dec. 7. Those include funding for the departments of Homeland Security, Commerce, State, Justice and Interior, among others. With limited time before the end of the year, all the bills will need to pass as one big omnibus, which means any sticking point could upend the whole thing. Which brings us to …

What’s the major sticking point?

Simply, the biggest issue is funding for President Trump’s border wall. It’s his signature issue, one that he’s been promising since the early days of his campaign (back when Mexico would pay for it) and now he says he’d allow the government to shut down if the spending package doesn’t include $5 billion for his wall. The Democrats have conceded to $1.67 billion for enhanced border security, but Trump isn’t satisfied. Meanwhile, some Democrats wonder why a deal was made in the first place, especially one that didn’t include protections for dreamers, the undocumented immigrants brought to the United States as children.

Wait. You said the Justice Department would shut down? What about the Mueller investigation?

Just because the government “shuts down” doesn’t mean everything grinds to a halt. Essential personnel keep working, and federal programs often have enough funds to keep operating. The special council currently investigating Russian interference in the 2016 election would continue its work. Special counsel Robert S. Mueller III’s office is “funded from a permanent indefinite appropriation and would be unaffected in the event of a shutdown,” a Justice Department spokesperson told CNN Wednesday. “The appropriations bills before Congress do not touch" the special counsel’s office.

So, what would shut down?

That’s hard to say. The agencies are all responsible for putting together shutdown contingency plans. But if prior government shutdowns are a guide, perhaps the most visible effect is the closing of national parks across the country. Hundreds of thousands of federal workers could be furloughed without pay (though Congress usually approves back pay). But most of the government’s most pressing responsibilities continue, according to the Committee for a Responsible Federal Budget:

In prior shutdowns, border protection, in-hospital medical care, air traffic control, law enforcement, and power grid maintenance have been among the services classified as essential, while some legislative and judicial staff have also been largely protected. Mandatory spending not subject to annual appropriations, such as for Social Security, Medicare, and Medicaid, also continues. Other examples of activities that continue are those funded by permanent user fees not subject to appropriations, such as immigration services funded by visa fees.

Remind me what happened in the last shutdown?

There as a shutdown for two days at the beginning of this year, but the biggie was in 2013. It was fall 2013, and the major fight was over funding the Affordable Care Act. Republicans in the House refused to fund the government unless Obamacare was defunded. The idea to hold the rest of the government hostage to kill the health-care law was spawned by Sen. Ted Cruz (R-Tex.). You may remember his 21-hour filibuster, in which he famously read his daughter “Green Eggs and Ham” through C-SPAN. But as the shutdown wore on, some moderate Republicans realized that optically they were going to be blamed for it and started working on a plan to get the government running again. Slowly they peeled off enough Republicans to support reopening the government. The bill passed with all Democrats and 87 Republicans supporting it, a rare moment when the majority leadership let a bill come to the floor knowing it wouldn’t receive majority support from its caucus.

Was there any political fallout last time?

Yes and no. Immediately after the 16-day shutdown, the public overwhelmingly blamed Republicans. But by next year’s midterms, Republicans expanded their majority in the House and took over the Senate, so they gained power. Now, that is probably despite the shutdown shenanigans, not because of them, but voters didn’t hold it against them for long. So, while it’s likely that Republicans would get blamed again if the government shuts down this time, it’s hard to say what the long-term electorate effects of that will be. (In other words, will anyone care by 2020?)

So what now?

Well, on Tuesday, Senate Minority Leader Charles E. Schumer (D-N.Y.) and presumptive incoming Speaker of the House Nancy Pelosi (D-Calif.) are headed to the White House for a private, no-Republicans-invited, sit-down with Trump to discuss funding the government. Trump seems to like “Chuck and Nancy,” and it wouldn’t be unheard of that they emerge with a deal that is later scuttled by Republicans in Congress. The pressure is going to be on Pelosi not to make a deal, though, especially since she still needs her caucus’s support to secure the speakership in January. What’s likely to happen is that they’ll agree to a continuing resolution (the technical name for kicking the can down the road) to keep the government funded until at least Dec. 21.

But it’s Christmas!

Yes, and there’s nothing lawmakers hate more than spending the holidays at the Capitol. Their eagerness to get home could motivate them to get these bills done, but that doesn’t solve the problem of Trump threatening not to sign anything without border wall money. And it wouldn’t be unprecedented for Congress to work through the holidays. In 2009, the Senate stayed to vote on the Affordable Care Act and passed it on Christmas Eve. Then, in 2012, both chambers spent New Year’s Eve in the Capitol to negotiate a deal to avoid a “fiscal cliff.”

This seems like a really inefficient way to govern, no?

Yes, and it’s somewhat of a recent phenomenon, particularly this now-common occurrence of bringing the government right to the brink of shutting down because Congress can’t get through the appropriations process. It’s more than a little ironic that this battle is getting sidelined to memorialize Bush who, as president, worked with Democrats in Congress to balance the budget through tax increases and spending cuts and who said during his inaugural address, “The American public did not send us here to bicker.”